The purpose of the current proposed research project is to increase understanding of how the brain accomplishes recognition memory. Recognition memory is the ability to discriminate between things in our environment that are novel and those that are familiar to us. The specific goal is to identify which brain regions are important for this ability, with the broader goal of adding to our understanding of brain mechanisms of human memory in general. Prior research has emphasized that there may be two ways in which one can recognize something as having been previously encountered, recollection and familiarity. Recollection refers to recognition that includes a rich subjective experience of remembering contextual or other detail associated with the recognized item. Familiarity refers to a general sense that we have encountered something before, without any associated contextual detail. Research into the brain mechanisms of these two processes associated with recognition memory have attempted to identify the brain structures that are important for these two kinds of memory, with a particular focus on the medial temporal lobes, which we know to be generally important for long-term declarative memory. Some research has suggested that recollection and familiarity depend on different substructures in the medial temporal lobes, particularly the hippocampus for recollection and the perirhinal cortex for familiarity. The current proposal aims to address the question of differential functions of different medial temporal lobe structures with regards to recognition memory, by using functional magnetic resonance imaging to explore how activity in these regions changes as we modulate the strength of a person's memory along different dimensions that correspond to recollection and familiarity. The results of these studies will shed light on the functions of these brain regions in different aspects of human memory, will provide important information about the specific mechanisms whereby these regions subserve memory processes, and will have implications for understanding how brain damage and normal aging may affect different kinds of memory differently. PUBLIC HEALTH RELEVANCE: The current proposal aims to address the question of differential functions of different medial temporal lobe structures with regards to recognition memory, by using functional magnetic resonance imaging to explore how activity in these regions changes as we modulate the strength of a person's memory along different dimensions that correspond to recollection and familiarity. The results of these studies will shed light on the functions of these brain regions in different aspects of human memory, will provide important information about the specific mechanisms whereby these regions subserve memory processes, and will have implications for understanding how brain damage and normal aging may affect different kinds of memory differently.